Cotton Association of India members including President Atul Ganatra and Director PG Patil on Wednesday were addressed by the distinguished agricultural scientist Dr. CD Mayee who specializes in cotton about the recent spate of pink bollworm occurrences that devastated cotton crops in Maharashtra and Telangana states in the second half of 2017. Among other illustrious positions, Dr. Mayee holds the prestigious post of president on Indian Society for Cotton Improvement (ISCI).
The focus of Dr. Mayee’s lecture was on how to manage pink bollworm. At the onset he expressed the opinion that the cause of the pink bollworm attack was mainly technological mismanagement and authorities not paying heed to timely warnings sounded by the team of scientists who were aware of the perils of continuous cotton farming without crop rotation.
Dr. Mayee spoke elaborately on the steps to be taken by farmers and how awareness can be generated among the farmers to adhere to these steps to prevent any further occurrence of this pest. Excerpts from Dr. Mayee’s presentation that throw light on how to circumvent this menace are reproduced below.
It’s recommended that the farmers uproot and destroy the cotton stalks and stubbles in the field before February 2018. They should carry out deep ploughing in the month of March-April, 2018 and allow full exposure to solar heat of May, a natural soil solarization.
Ginners and market yards should be provid4ed with pheromone and light traps to maximize the moth catches immediately. It would be useful to set up four to five light traps per ginnery or market yard. It is recommended that farmers choose only those hybrid varieties of 140-160 days duration and avoid pre-monsoon sowings in May 2018.
It’s crucial that the farmers resort to timely sowing at the onset of monsoons. At village level collective decision of sowing only a few sets of hybrids/varieties with equal duration and within a time span of a week would go a long way to manage the pest.
There are refuge seed bags provided with the regular Bt seeds to cotton farmers. The cotton farmers should diligently sow the refuge seeds that are susceptible to the pest along with the regular seeds so that even if the pest attacks it constrains itself to the refuge seed plants for food. The rest of the cotton crop remains undamaged. It is recommended that at least two rows of refuge seeds are sown around the main Bt cotton plots.
The farmers should take care to plant some okra seeds adjoining the cotton plots which will fruit around November. This will act as a trap crop for pink bollworm and also serve to give warning signal for possible pest infestation.
The activity that required most diligence that was recommended was usage of pheromone traps. The scientists said that by August end, 4-5 pheromone traps should be in place per hectare of land. This should be done in at least one field in a village and for a minimum of 100 villages that are sprawled across the cotton growing districts. Besides, the lures of the traps have to be changed every fortnight.
The step involves monitoring the economic threshold level (ETL) of the pest and when the ETL is crossed, the farmers must undertake measures for containment. The ETL level as given by the scientist was 24 moths trapped for three consecutive days or 8 moths per day for consecutive three nights in at least 2 traps per field.
The scientist also suggested an alternate method of monitoring. The farmers can open green bolls to inspect the presence of pink bollworm larvae. The ETL in this case is 10 percent damaged green bolls out of 25 plants randomly examined.
When the moth catches or green boll damage exceeds the ETL, undertake the spray of Chlorpyriphos or quinalphos or thiodicarb during mid-September and any synthetic pyrethroid in December. This should be done only when the plant has 8-10 green bolls. Usually, it happens in irrigated fields. In addition, care should be taken that the insecticide sprays are performed to protect the green bolls only after picking of early seed cotton.
In the first three months of cotton growth the farmers should not use insecticides like synthetic pyrethroids, phenomyl, or any growth promoting substances. The farmers should also strictly avoid use of chemical tank mixtures including PGPR, botanicals, hormones, pesticides, nutrients and so on.
The recommended norm also stated that fertilizer applications should be as per schedule. Basal dose of half of nitrogen, full dose of phosphorous and one third of potash was the stipulated aggregate dosage. The remaining dosages of nitrogen and one-third potash should be given at 30-35 days after sowing. The left over potash should be used as a supplement at 65 to 70 days after sowing.
The scientist in addition cautioned the farmers that the safest insecticide schedule suggested by research institutes should be adopted when the pest damage is detected. In concluding, the scientist also gave indication of how the pink bollworm infection can be detected early physically.
The signs to look for early detection include, squares remaining stunted and their failing to open; rosette flowers having improper opening of petals; Black dots on green bolls followed by exit holes of 1.5-2.0 mm diameter and pink bollworm moths trapped in the pheromone lures.